Bone Fractures in Vegan Nuns

In 2011, a follow-up (1) of an earlier study on vegan Buddhist nuns (2) was released. After two years, the vertebrae of 88 vegans and 93 omnivores were examined using x-rays. Ten women (five vegans and five omnivores) had sustained a new vertebral fracture after two years; there was no significant difference between the two groups.

Rates of bone mineral density (BMD) change were examined at the lumbar spine and femoral neck with a variety of associations found. Lumbar BMD increased with age, lean body mass, and vegetable fat; and decreased with vegetable protein and steroid use. The authors suggested that the increase in BMD of the lumbar spine was possibly due to osteoarthritis and, therefore, not a healthy phenomena.

As for the femoral neck, BMD increased with both lean and fat body mass; and decreased with age, animal fat, and ratio of animal protein to vegetable protein. This would indicate that animal protein had a negative impact on bone. To make this even a bit more complicated, the food questionnaires used by the researchers indicated that the vegans were only eating an average of 1,093 calories, 36 g of protein, and 360 mg of calcium per day. The estimated energy requirement for women their age and size is about 1,600 calories which indicates that the food intake of the vegans was possibly underestimated by one-third. The non-vegan nuns had intakes of 1,429 calories, 62 g of protein, and 590 mg of calcium per day which seems more likely.

In summary, compared to non-vegetarian Buddhist nuns, vegan nuns had a similar rate of vertebral fractures, but it is not clear how accurate were the associations with changes in BMD.

Commentary not added to VeganHealth.org:

Ten fractures in 181 women in two years seemed high to me, so I did a bit of searching and found a study (3) that indicated that in Hong Kong and Japan, the rate of vertebral fracture in women over 65 is 594/100,000 person-years. I calculate the person-year fracture rate in this Buddhist nun study to be 2,762/100,000. That’s obviously quite a bit higher, but it should be noted that the fractures in the Buddhist nun study were determined by giving an x-ray to each subject, rather than reporting a bone break, and would likely find more fractures than the study determining the 594/100,000 rate.

This entry was posted on Wednesday, September 14th, 2011 at 4:43 pm and is filed under Bones. You can follow any responses to this entry through the RSS 2.0 feed.
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